I am purchasing a Trac Lok Posi rear end for my T-Bird, It has the 8.8 rear in it. I am trying to decide what gears to go with. The car has a Marauder T/C and flexplate, true dual exhaust, and a 4R70W transmission, which is getting replaced with a different one, that will be JModded (for anyone who knows what that means) I am also going to be putting in a DOHC 4.6 from a Mark VIII this winter. I do drive this car on a daily basis, but I would like to have fun with it at the track as well. I am torn between 3.73’s and 3.55’s, 3.73’s of course will be more fun, and 3.55’s would be an improvement, and practical, and better for day to day use, but not nearly as fun at the track. What would everyone else here choose. And how much could I expect to pay to get them installed…cough…cough…Jeff.
3.73… don’t sell yourself short… f it.
Is the tranny overdrive?
If it is go 4.11
if it is not go 3.73
but do not waste time with a 3.55 or lower number. Your car ain’t exactly light, it needs all the help it can to get off the line. 
Unless you do a bunch of highway driving, you’ll be much happier with a steeper gear in the rear.
3.73 FOR SURE…
It does have Overdrive, it has the O/D button on the shift knob, so its like an overdrive servo or something, I guess. I think 4.10’s might be pushing it…as cool as it may be, my highway cruising RPMs would be at like 4500 or something crazy like that
4.10 r rough for cruisin…i had them in my s10 and even wit over drive the tach was up there…it wasn’t REAL bad … and gas milage was shitty…
18 gal tank i got 310 miles all turnpike driving
and about 250ish around town
around town, with some highway driving, I can get about 215 miles out of a tank of gas…it lasts me about a week. Damn V8!
GM gearing and little tires arent hte same final ratio as Ford
you have a 4.6 they like to rev. you need gears. get the 410s. with a true 26" tall tire and my old AOD i would cruise at 2700rpms
now im sure your trans has similar gears. 2700rpms isnt as bad as you think and around town will help mpg since youre not using as much motor. fords autos like to suck up alot of power
Does anyone make a 3.90:1 for the 8.8? (39:10 gear counts)
4R70W 4th gear (stock) is 0.67:1 ratio overdrive.
If you go with a taller tire ( P255/60R16 ? ), the calculator tells me that a 4R70W and 4.10:1 rear gears and 28" tall tire should put the motor at about 2200 RPM at 65.
if you get the 3.73’s or lower, in a year or so you will wish you had a steeper gear.
Like quik said, you have a heavy car and a motor that is happier at high rpm’s. Not the best combo for drag racing or stoplight to stoplight “cruising”. 4.10’s won’t be that bad on the highway and will be tons better around town.
i figured that much i was just try’n to give him a rough idea
oh and i don’t have little tires mine are 26.25" tall tires which are the ame as the stock over all diameter
I can get MotiveGear Ring and Pinions for about $130 a set, so maybe I will get 3.73’s and 4.10’s and see which one I like better. Unless someone here can get them cheaper. 8.8 rear end, 28 spline for anyone who may sell them.
If you’re getting 4.10’s you might as well get 4.56’s. :D:D:D:D:D:D
I think you will like the 4.10’s a lot better than your other choices. good luck
I hjave no doubt in my mind that 4.10’s will be alot more fun, I just wasn’t sure if it was practical, seeing that this car is a daily driver
grow nads and get 410s, hell im going 456 in my DD
not this again, sorry none of them are worth any time
ok…im getting 4.10’s:burnout: …damn peer pressure:finger2: 
either way, 373 are not bad at all for DD i have 410s in my DD but then again it has taller tires and no OD. i would prob go with 373 IMO